The purpose of this Master's thesis is to contribute to a better understanding of children's free time reading book practices by studying pupils in the school library and their processes of finding and borrowing books for themselves to read silently in the classroom, so called free time reading books. The study also includes observations of the staff's role, particularly the school librarian's in supporting pupil's book selection. The empirical material consists of field notes from an etnographic study where pupils in 4th grade (aged 10-11) and staff were observed during three school library visits. The theoretical framework is inspired by Lennart Björneborn's concepts of information practices in libraries: serendipity, integrative library interface, mediation flow and affordance spaces. The study shows that pupils' search for free time reading books in the school library is relatively routine-based at the same time as it is spontaneous. The process is an interplay with factors such as time, display and interaction in the integrative library interface. In the presence of adults, finding books becomes an imposed task for the pupils. The staff works within a set hierarchy in the school library where the teachers support the librarian by administrating the visit and the librarian helps the pupils to find books. A library practice of selecting books, a free time reading book practice, emerges as rather routine and instrumental.